Hello Jani,
> -----Original Message-----
> From: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> Sent: Monday, June 26, 2023 5:52 PM
> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@xxxxxxxxx>; intel-
> gfx@xxxxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH 1/2] drm/i915/color: Add function to load
> degamma LUT in MTL
>
> On Mon, 26 Jun 2023, Chaitanya Kumar Borah
> <chaitanya.kumar.borah@xxxxxxxxx> wrote:
> > MTL onwards Degamma LUT/PRE-CSC LUT precision has been increased
> from
> > 16 bits to 24 bits. Currently, drm framework only supports LUTs up to
> > 16 bit precision. Until a new uapi comes along to support higher
> > bitdepth, upscale the values sent from userland to 24 bit before
> > writing into the HW to continue supporting degamma on MTL.
> >
> > Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/display/intel_color.c | 42
> > ++++++++++++++++++++--
> > 1 file changed, 40 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_color.c
> > b/drivers/gpu/drm/i915/display/intel_color.c
> > index 8966e6560516..25c73e2e6fa3 100644
> > --- a/drivers/gpu/drm/i915/display/intel_color.c
> > +++ b/drivers/gpu/drm/i915/display/intel_color.c
> > @@ -1498,6 +1498,38 @@ static void glk_load_degamma_lut(const struct
> intel_crtc_state *crtc_state,
> > ilk_lut_write(crtc_state, PRE_CSC_GAMC_INDEX(pipe), 0); }
> >
> > +static void mtl_load_degamma_lut(const struct intel_crtc_state *crtc_state,
> > + const struct drm_property_blob *blob) {
> > + struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> > + struct drm_i915_private *i915 = to_i915(crtc->base.dev);
> > + struct drm_color_lut *degamma_lut = blob->data;
> > + enum pipe pipe = crtc->pipe;
> > + int i, lut_size = drm_color_lut_size(blob);
> > +
> > + /*
> > + * When setting the auto-increment bit, the hardware seems to
> > + * ignore the index bits, so we need to reset it to index 0
> > + * separately.
> > + */
> > + intel_de_write_fw(i915, PRE_CSC_GAMC_INDEX(pipe), 0);
> > + intel_de_write_fw(i915, PRE_CSC_GAMC_INDEX(pipe),
> > + PRE_CSC_GAMC_AUTO_INCREMENT);
> > +
> > + for (i = 0; i < lut_size; i++) {
> > + u64 word = mul_u32_u32(degamma_lut[i].green, (1 << 24)) /
> (1 << 16);
> > + u32 lut_val = (word & 0xffffff);
> > +
> > + intel_de_write_fw(i915, PRE_CSC_GAMC_DATA(pipe),
> > + lut_val);
> > + }
> > + /* Clamp values > 1.0. */
> > + while (i++ < glk_degamma_lut_size(i915))
> > + intel_de_write_fw(i915, PRE_CSC_GAMC_DATA(pipe), 1 <<
> 24);
> > +
> > + intel_de_write_fw(i915, PRE_CSC_GAMC_INDEX(pipe), 0); }
>
> Please adjust glk_load_degamma_lut() instead of copy-pasting the entire thing
> with small modifications. One of which is breaking dsb use.
>
> You'll probably also want to add small conversion helpers between 16 and
> 24 bits instead of doing them inline.
>
Thank you for the review. I have sent a new version of the patch set with the comments addressed.
I look forward to your comments.
Regards
Chaitanya
> BR,
> Jani.
>
>
> > +
> > static void glk_load_luts(const struct intel_crtc_state *crtc_state)
> > {
> > const struct drm_property_blob *pre_csc_lut =
> > crtc_state->pre_csc_lut; @@ -1635,11 +1667,17 @@
> > icl_program_gamma_multi_segment(const struct intel_crtc_state
> > *crtc_state)
> >
> > static void icl_load_luts(const struct intel_crtc_state *crtc_state)
> > {
> > + struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> > + struct drm_i915_private *i915 = to_i915(crtc->base.dev);
> > const struct drm_property_blob *pre_csc_lut = crtc_state-
> >pre_csc_lut;
> > const struct drm_property_blob *post_csc_lut =
> > crtc_state->post_csc_lut;
> >
> > - if (pre_csc_lut)
> > - glk_load_degamma_lut(crtc_state, pre_csc_lut);
> > + if (pre_csc_lut) {
> > + if (DISPLAY_VER(i915) >= 14)
> > + mtl_load_degamma_lut(crtc_state, pre_csc_lut);
> > + else
> > + glk_load_degamma_lut(crtc_state, pre_csc_lut);
> > + }
> >
> > switch (crtc_state->gamma_mode & GAMMA_MODE_MODE_MASK) {
> > case GAMMA_MODE_MODE_8BIT:
>
> --
> Jani Nikula, Intel Open Source Graphics Center
